For any square, the length of one side is s.
A square has four sides of equal length.
The perimeter of the square is the sum of the lengths of the four sides.
P = s + s + s + s = 4s
Now we compare the perimeter with one side.
The ratio of the perimeter to one side is 4s/s = 4/1 = 4:1
The perimeter of every square is proportional to the length of one side of the square, and the ratio of the perimeter to one side is 4 to 1.